SOLVED! Alternator not charging-not the alternator

[Reprise]

Put in a new HO alternator in the Sierra about a year ago, not long after I upgraded to dual e-fans.

Since then, I replaced the fan harness (the 'new' new one is fine), and up until today, my charging system was fine.

Today, I started the truck, had the (bus) issue where the radio doesn't output sound, and shut it off. It's very intermittent, and not (?) related to what I'm about to relay...

Restarted, and the radio worked again (as per normal), However, I immediately saw "battery not charging" on the info display, along with the battery lamp and the gauge pointing three notches from the bottom). Figured something 'glitchy' happened, shut down, restarted again. Nope. Same error.

I was about 20mi from home, and knew the battery had > 12.00 volts in it, thanks to the BT monitor I have on it. Shut off my radio and HVAC, rolled up my power windows (just in case), and managed to make it home.

Broke out the multimeter in the driveway, and the battery registered with 11.25 volts. So not 'trashed'.
I put a charger on it, and once it's had about 30min to settle down afterward, I'll measure again. I fully expect it to be holding 12.xx volt, but we'll see.

Didn't have any little critters chewing wires, etc., and connections are tight. That leaves the alternator to check, which I'll do once the battery settles down and I restart the truck.

Checked on where I got the battery... came from Amazon. And... warranty expired two months ago (14mos). I probably have 2000 miles / less than 100hrs on the unit.

Need: at least a 145A unit; that's what came with the truck (which didn't have e-fans). I'd like a boost from that (like 200A or better), but would settle for a 145A unit. The one that came with the truck was a remanned 145A (in the nice Delco DR44 case). It actually still works, so I'll put that back in in the short term, so I can get my trailer back home.

I'm tempted to get one from one of the national retail auto parts (RAP) chains, as they'll have a 'lifetime warranty', even though we know they often fail, but I figure a new one would only be a short drive away, in an emergency. Feel free to talk me out of that option.

Rock has the AC Delco, but it only has a 12mo or 24mo warranty, depending on option. There are some chinese (?) options from Rock with a lifetime warranty, but if it fails, I'm waiting for Rock to ship a replacement, and I don't like being potentially much farther from home with the trailer, if it goes out.

Yes, I'll start carrying the 'old' remanned DR44 with me now, so I can swap it out when (?) the next one goes out. At least it's in a more accessible place than in the 4.2L engine bay... LOL

For reference, the 'lifetime' option at Rock is from TYC (likely cheap chinese crap). Another, BBB, has a 3/36 warranty. No new AC Delco option available. The remanned AC Delco is 2yr / unlimited miles (same as the 'old' one I have that's still working, so no point spending $ on the same thing that I already have). I don't mind paying a little extra, if I can trust the manufacturer.

Outside of the e-fans, I'm also planning a winch for occasional (emergency) use, and I have a 1400W Pioneer amp that I'm going to wire up at some point (more for headroom, not SPL) I doubt I'll ever use the amp at more than 50% gain output, and may only use it for a sub (a reasonable 8" or 10" Alpine, nothing monstrous). But right now, the e-fans are the only thing that would pull anything other than a stock electrical load (again, 145A was OEM for my truck).

Maybe I'll make a poll out of this, for quick responses.
Poll will close in seven days after 9/12/23

 

[TollKeeper]

RAP for me. Nothing like having the convenience of a local parts store for a replacement.

There was a 160amp alternator on the 2005-06 models, but it is a 2 wire alternator, vs the 4 wire of the 145amp.

 

[Mooseman]

My experiences are on the old 4.2:

Remi: fail
ACDelco reman: fail
CCC new off-brand: survived and still have it when I scrapped the truck (incompatible with my 07)

Any way to make the later years with efans and higher output work in yours?

Or maybe you just need to pony up the cash and get a high output unit.

 

[Reprise]

Any way to make the later years with efans and higher output work in yours?

Or maybe you just need to pony up the cash and get a high output unit.

No... the new one I bought 14mos ago was a 220A -- which should be 'HO enough'. (FYI)



Update: Swapped out the alternator to the old reman (Delco) that I swapped out for the 220A that 'failed'.

Bad news -- I have the same issue, and am now 'in trouble', as I have my camper 22 miles away, and it has to leave its site by 3pm tomorrow.

So... both my HO alternator and my old reman measure output of 00.3x volts, on the alternator 'hot' lug, grounded to the battery negative (and other places). Am charging up the battery again, which ended up at 12.25 after charging it for an hour / resting 30min. It's now at 10.xx (-? not sure; forgot) after running the engine twice for only a couple of minutes each time.

I also removed my in-line battery isolator and connected the negative cable directly to the battery (-) terminal -- same output, no charging.

Am probably going to start looking at grounds next, but it's now almost dark (and I'm not supposed to be working on vehicles in the driveway in the first place -- thanks, HOA!)

Backup plan is to get a U-haul pickup and get the trailer back to the storage unit. I can extend the camping pass one more day (to Friday 3pm), but it *has* to be out by then, as someone else has the spot. Driving back to the trailer now so I can finish the project I was working on, and get it packed away and ready to travel tomorrow, if possible.

(mods: If you want to copy my posts to a new, more relevantly titled thread (like: "oh sh!t, my truck isn't charging my battery" ... lol) ... feel free. Looks like I don't need an alternator.

I have the AGM in the Envoy I can swap in for the FLA in the Sierra, but the battery is accepting charge, and the truck is still starting (but I don't want to retrieve the trailer and risk having the rig break down in traffic before I can get the trailer back to its storage site (about 15mi away).

Yes, I have a gas genny, and should be able to charge the battery from that, if I needed to.
The only electrical load would be brake lamps, turn signals, and my trailer brake controller. I'm pretty sure I could make the 15mi w/o the TBC.

 

[Sparky]

My experience with a handful of alternators as I've managed to always need to replace one at some point:
Camaro: Put a Remy in it (obtained at a RAP) has always worked ok but the cam lope causes some fluctuating output at idle. Might not really be the alternators fault though.
Trailblazer: Put a Remy in it (again, from a RAP) when the OEM's bearings started going and it began to whine like a banshee. Never had a problem with it over the next 3-4 years until the TB died of rust cancer.
Silverado: Slapped a Duralast Gold in it when the OEM alternator stopped charging. Never had a problem with it for the next 3-4 years until I traded it in.
Civic and Odyssey: they don't have enough miles to have failed on me yet lol. Almost had to on the Civic because it seized up on me from sitting, but got it working again.

My opinion: go with RAP because IF something happens, just swap it out.

Also - I wouldn't be too worried about using a 145 amp alternator on your truck with e-fans conversion (unless you have a bunch of other power hungry stuff). In 2007 they went to e-fans on the new style 1500 and they still kept the 145 amp alternator, and I never had any power issues. Some of the cheaper higher amp alternators what they don't tell you is you won't get that amperage out of it until something silly like 3000 RPM engine speed or whatever, which makes it basically useless anyway.

 

[Mooseman]

Changed the title.

Ok so the alternator is not at fault. Maybe the signal wire is broke? Checked the fuses? Any way you can jump the signal wire to make it work independently of the PCM?

I'm thinking it's not a ground as the truck wouldn't start or crank at all but it's still worth verifying. Are you seeing 12v+ at the battery wire on the alternator post? Are you sure that alternator was good? If you have a pick n pull nearby, maybe grab one from there cheap and give it a try. Sometimes you can find a recently installed one before it was junked.

 

[TollKeeper]

Take the one that is already off the truck to a local parts store, and get it tested...

If it tests bad, than take the one off the truck, and get it tested.

 

[Reprise]

New update: Got the trailer ready to go last night, and went and extended my stay this morning (bought myself a little time). Also found out that there should be sites available in other areas, if I wanted to keep the trailer there a few more days (my house is getting a new roof starting Monday, so it would be good to be away for the pounding.)

Drove the Accord home, and hoped I'd find the battery *not* fully charged (if it was, then the battery would not be the culprit.). Some *hopeful* news... it was still 'charging' (per the indicator light on the charger). Resting it for 30min right now and will take a voltage reading then. If it shows '12.25' volts, which is what it has been showing over the last day or so... then I'm pretty sure it's the battery, and I'll swap in the AGM that's in the Envoy now, to verify. The Sierra's battery has been well-maintained (some might say 'overly' maintained), but it was new in 2019 (-? have to check). That's 5 years, and the end of its warranty. Hoping it just gave up the ghost, without warning.

Next update in an hour or so...

 

[Reprise]

Still futzing around with this, and I now know it ain't the battery, either. AGM was hooked up, and while the in-dash ammeter showed improvement, it was still nowhere near 12V, and I still have the 'battery not charging' message, battery light, etc.

AGM SoC was at 12.12V; plenty enough to start the truck with. I did notice after a couple of minutes of running the engine that SoC was still 12.12 after I shut her down. Gotta love slow-drain AGM batteries.

Got out the creeper and looked underneath -- no evidence of any wildlife chewing anything, nothing disconnected. The small cable that goes from alternator to the 'B+ Battery box' is different on the Envoy, or I'd swap them out next. That cable is also marked on the wiring jacket as 'fusible link' (it's an 8ga wire, apparently). It doesn't look compromised, and the connection is tight at both ends. But it's $10, so I ordered one up at the nearby RAP (AZ) and am off to get it now.

Apparently, there's a relay somewhere on one of the battery cables (?) That'll be the next thing I load into the parts shotgun.

Truck still starts / runs. Just doesn't charge the battery. Ugh...

 

[mrrsm]

As Ground aspects have been mentioned frequently in the prior responses ...you've likely already done this. But since it might be Unconventional Thinking for most Folks to try to Read Resitance versus Reading Voltage...and... because by the time ALL of the System Voltage gets back to the Negative Battery Terminal...it should be reading N2N (Next To Nothing).... taking THIS approach is worth making mention of here:



Source:

GMC Sierra 1500 bad alternator symptoms, how to check voltage

The alternator is the power station of GMC Sierra 1500 that converts mechanical energy from the engine to electricity. It not only powers all the...

www.wheelsjoint.com

 

[Reprise]

Success! (surprised me; I didn't think this was going to work)

That little 11" cable (fusible link) between alternator stud and the red battery box was the culprit. Put the new one in, and voila! (that was for you, Moose... sorry, no diacritical Dash gage showed +14V charging, and the meter registered 14.23 at the battery terminals. Problem (should be) solved!

I need to snug everything up, torque up the alternator mounts, etc., and then take her on a drive and monitor. But we're looking good!

My thanks to everyone who responded with ideas / suggestions. As always... appreciated.

As for the cause... for now, I'll suspect the 220A alternator I had in there caused the wire / fusible link to crap out. Will purchase another one of these wires before I put that alternator back in; if the new wire also craps out... then I know it's the new alternator, and will have a ready replacement on hand to fix it.

The other possibility would be something with the wiring harness for the e-fans, which is connected to that same stud for power (per the vendor). But that harness is a real quality piece, so I don't suspect it, for now. And my fans continue to work fine.

For now, I'm rolling with the old alternator I took out (which wasn't broken, and is putting out 14A, so I'm perfectly fine in the short term).

 

[TollKeeper]

On the TahoeYukon Forums, I know I have read about the E-Fans causing issues with the electrical.. But I cant find the specific thread about it.

 

[Mooseman]

Going from 145 to 220A is likely the problem as that link is likely rated for the 145. Over time, it probably just melted.

 

[Reprise]

Going from 145 to 220A is likely the problem as that link is likely rated for the 145. Over time, it probably just melted.

I think you're right. Although, as I said... I really can't see a difference from the outside. Am going to slice through it and if anything interesting, post a pic. AFAIK, it's the original one (so, 20MY old)

According to what I saw yesterday, the OEM is an 8ga wire; it can be replaced with an 4ga (and some ppl do so as part of a 'big 3' wire upgrade, which I'll eventually get to). For now, I'll keep it at OEM spec until I know more about how it operates and how the 'fusible link' portion safeguards things, etc., rather than just indiscriminately slap a 4ga on there, call it a day, and watch the truck burn to the ground, someday.

As for the truck, it's operating just fine, and I got the trailer out of the campground w/o issue.

The truck actually cranks a little better with the AGM battery from the Envoy, so I'll keep it in the Sierra and use it. It's actually a year older, from 2018. But I think it has a 7yr (or maybe even 10yr -?) warranty. I know it self-discharges / drains verrrry slowly, at least in the Envoy. Would buy another one for that reason alone.

As an aside, lithium batts are getting super cheap. But I've taken such good care of my two 6V for the trailer (keeping them float charged, watered, etc.), that I've probably still got years of usage left out of them. Yay me. Only downside is that when I take them out of the battery box on the tongue, I have to be careful not to tilt them, or I'll get battery acid on my clothes.